Holes In Cannabis Leaves: Common Pests That Attack Cannabis

It’s another day of you taking care of your plant. You start by checking the ambient environment, checking the nutrient solution, and watering your cannabis plant. And you decide to give your plant a nice little trimming but as you bend down, you’re met with horror — your plant’s leaves have holes in them.

Now unless there was a miniature Star Wars battle going on on your cannabis plant, you need to be worried. Holes on leaves are a sign of bugs and pests that are mistaking your precious plant for their breakfast, lunch, dinner, and everything in between.

But what pests may be causing this? And what can you do about it? We’ve got your back. In this article, we discuss the most common bugs and pests that can leave holes in cannabis leaves along with some nifty ways of dealing with and preventing them. Read on to know more. 

1. Caterpillars 

Caterpillars are cute, aren’t they? They come in various colors and look pretty chilling on the leaves of plants. But don’t let them deceive you — they are an enemy to your cannabis plant, and you must treat them as such. Underneath the cute colors lies a pest that eats away the leaves of your cannabis plant. 

Let’s get some context. Caterpillars are larvae of moths and butterflies, and so far, scientists have discovered over 175,000 species of caterpillars around the world. Most of these species are 1 mm to 15 mm long. But unlike other larval species, these pests have ten legs, twelve eyes, V or Y-shaped cleavage lines, and crochets on the prolegs. 

Granted, caterpillars are fascinating creatures with much more to admire than colors. They lead fascinating lives, have their own social behaviors — form alliances with ants — and feature a chemical-based defense mechanism. 

But caterpillars are herbivores and they love devouring plants as much as your cat enjoys catnip. Within a short time, caterpillars can significantly damage your cannabis plant by leaving tiny holes in the leaves, especially the fan leaves. They can even kill your plant if they are left to do their thing. 

But you don’t have to worry much since only a few select species of caterpillars are damaging to plants, such as cabbage loopers or inch worms. When these species attack your plant, they start eating away the tender leaf tissue, which can hamper the photosynthesis process. 

Talking about caterpillars, you should also be wary of cutworms. Cutworms are destructive pests notorious for damaging cannabis plants and seedlings. As caterpillars from the moth family, these insects can be found causing damage in agricultural fields, gardens, cannabis fields, and indoor grow rooms as well. 

Cutworms are nocturnal and hide in the soil or plant debris during the day. They feed at night on cannabis leaves and stems, and when they've grown large enough, they'll feed on the roots, too.

They get their name as "cutworms" because they typically chew through plant stems right at or just below the soil line, causing seedlings to topple over. So, if you notice that the seedling was fine the previous night and is gone this morning, it could be due to cutworms. 

Identifying Caterpillars on Cannabis

You’ve already found holes in your cannabis plant, but that can happen due to many pests, not just caterpillars. So, how do you know for sure if you are dealing with caterpillars or otherwise? Here are some signs to look out for.

Holes Around The Plant

Since caterpillars enjoy munching on leaves, look out for holes in your plant in seemingly random or irregular patterns. Caterpillars are not known for being neat and strategic, so they munch on leaves whenever they feel like. Additionally, look at the holes — they should be a couple of millimeters in diameter. 

Stem Damage

Caterpillars not only munch on leaves but they do a lot of damage to the stem. Fortunately, few species of caterpillars munch on stems, like the Eurasian hemp borer. Such species love to feast on the dense stem tissue, so they bore a hole in the stem and get inside.

This can cause a great deal of damage to your cannabis plant. They weaken the structure of the plant and take away essential nutrients from it, leading to nutrient deficiencies in the branches that follow. 

Yellowed Leaves and Stunted Growth 

Another symptom of a caterpillar infestation is slowed growth and yellowed leaves — a sign of a plant that’s losing its health. This occurs due to a lack of photosynthesis in the leaves; your plant can no longer produce enough energy to sustain itself, leading to the leaves yellowing and growth slowing down. 

Chewed-Up Buds

The worst-case scenario is when these insects start reaching the buds. Before you know it, caterpillars can start eating the resin on the buds; sometimes, they can even burrow in the buds and reach the base. Generally, this can cause the buds to wilt and die, leading to a lower yield, but if you are unlucky, you may find one in the grinder. 

2. Grasshoppers

Caterpillars are your biggest enemies if you are dealing with holes in your cannabis plant leaves, but the next big worry is grasshoppers. Quite similar to crickets in nature, grasshoppers love feasting on the tender tissues of the cannabis leaves. 

Fun fact: grasshoppers are considered the oldest living herbivorous insect species in the world. If they’ve survived so long, they’ve got to be fitter than the rest of the species around them. So, respect Darwin and don’t take grasshoppers for granted. 

Grasshoppers can deal a significant level of damage to your cannabis plant in no time; sometimes, they can completely wipe out your crop before you even know what happened. 

These insects start by eating the fan leaves and sometimes they even munch on the plant’s stems and branches. Essentially, they start tearing away pieces of the plant tissue, which not only takes away the nutrients from the plant but also makes photosynthesis an issue. 

Identifying Grasshoppers on Cannabis

Spotting grasshoppers is either easy or difficult, depending on how good you are at war games. Grasshoppers are big enough to be seen by the naked eye but they have a camouflage that helps them blend into certain plant species. So, apart from just looking for them on the canopy, here are some other things you should watch out for. 

Holes on the Leaves 

The first sign of grasshopper damage is holes around your cannabis plant, especially on the leaves and sometimes on the stems. When these insects puncture your plant, they not only make holes but also suck essential nutrients from the plant. They can also cause problems in the photosynthesis process. 

Mounds on the Soil 

Not all grasshoppers but some species of them like to dig holes in the soil. When doing so, they end up creating mounds on the soil’s surface, which somewhat resemble a tiny volcano. If this happens, they can reach the roots and start a feast there too. 

Leaves Turning Brown 

Next up, the leaves may start turning brown. This is a distinguishing feature between grasshopper and caterpillar damage. Essentially, grasshoppers cause a lot of stress to cannabis plants, leading to shock, which further leads to the leaves turning brown. 

Presence of Other Rodents 

Grasshoppers may be the oldest living species, but that doesn’t mean they’re the king of the jungle. They have many natural predators, and if you are growing cannabis outdoors, many of these predators may make their way to your garden looking for grasshoppers. 

But don’t mistake them for friendly or beneficial predators. Usually, various animals and birds follow grasshoppers, including foxes, birds, and rats. You don’t want these in your garden either as they can physically damage your cannabis plant in worse ways than a grasshopper might. 

3. Crickets

Crickets are very similar to grasshoppers, and like the two species mentioned above, even these guys love feasting on cannabis plants. Many people admire crickets for the sounds they make, but if you hear them chirping in your garden, it’s time to put on your gardening gloves and call it a war. 

Crickets are a threat to your cannabis plant. These insects feast on cannabis seedlings and plants, and in a short period, they can do a lot of damage to your cannabis plant. They can essentially destroy your plant and compromise its yield. 

These insects are also nocturnal, so they are more active at night. And usually, their body ranges from 1 to 2 inches in length. They come in various colors, including yellow, green, white, black, brown, and red. They also feature wings that lay flat on them, six legs, and two antennas. 

Identifying Crickets on Cannabis Plants

Fortunately, it’s fairly easy to spot crickets — it is as easy as it can get. Want to know how simple it is? Take these two questions:

1. Does your cannabis plant have holes in it, especially the fan leaves?
2. Do you hear crickets in your garden?

If your answer is yes, you don’t have to worry about anything else. But let’s not make it so simple, considering the damage these creatures can do to your cannabis plant. Here are some more signs you should watch out for:

• The leaves may start developing brown spots 
• You’ll find some burrow holes in the soil, which are often created by cricket species like mole cricket
• You may also find other animals and birds in your outdoor cannabis garden. 

4. Beetles 

Beetles can be a major threat to your cannabis plants. Some beetles can feed on various parts of your marijuana plants and can do some major damage if they go unchecked. Here's a look at some types of beetles that damage cannabis plants:

Japanese Beetles: Leaves that are eaten by Japanese beetles tend to look lacy with tissue being eaten between the veins.

Flea Beetles: These small, jumping beetles produce numerous tiny holes in cannabis leaves, and can cause damage to all areas of the plant throughout the growing season.

Blister Beetles: These beetles feed occasionally on cannabis foliage, but when they do, they defoliate the leaves and also make holes in them. 

Identifying Beetles on Cannabis Plants

It’s pretty easy to identify beetles as they aren’t as small as other pests. Take your time to examine the leaves closely, and pay attention to the upper and lower sides and stems. There are various types of beetles but they usually have antennae, six legs, and hard wing covers. 

Beetles come in various colors and the patterns differ too. While some beetles have a metallic green or blue sheen, others look black or brown. They are usually active and feed throughout the day so you can watch them crawl on leaves and fly around in your grow room. 

Check the leaves for signs of any damage caused by beetles. Usually, you will see irregular holes and skeletonized leaves with only veins remaining. In addition, inspect the leaves for frass — insect excrement that looks like webbing — indicating that there are larvae of beetles present in the plants.

Damage from beetles can have impacts beyond cosmetic damage or what you just see. For instance, when beetles feed on cannabis leaves, they remove leaf tissue, which is important for photosynthesis. This reduces the leaf tissue exposed to sunlight and the amount of chlorophyll available to capture that sunlight. As a result, the plants struggle to produce enough energy to support the physiological processes necessary for growth and exhibit stunted growth with diminished yield potential.

Apart from that, beetles devour a significant number of leaves, so the plant is often stressed and loses vigor. It also decreases the plant’s resources that can go toward growth and reproductive functions. Weakened plants are more susceptible to secondary infections by pathogens so the plant can be affected by many issues in a short period. 

To deal with beetles, use pyrethrin-based insecticides. Derived from chrysanthemum flowers, pyrethrins are effective against beetles and other insect pests. However, use them according to the instructions from the manufacturer and take care not to harm other beneficial insects. 

5. Snails and Slugs

The least common thing that may be eating your cannabis leaves are snails and slugs, but they can be a sign of trouble. These slimy creatures are slow but they have an appetite — they can eat a lot of leaves, causing damage to your cannabis plant. 

Capable of creating significant havoc if you don’t stop them on time, snails can be nasty. Yes, they're slow and don’t look like they pose a threat; however, you shouldn’t underestimate them. Instead, try and understand how they can affect the plants, methods to identify them, and finally, how to eradicate them. 

Since they are slow, it’s easy to assume that they won’t be much of a problem. After all, how many leaves can they possibly eat, right? However, remember that they can feed on plant tissue with reckless abandon, which can quickly add up if you don't check in on your plants frequently. They have a thing for tender leaves, and when they chew, they leave very large holes and strong jagged edges in foliage. 

You don’t have to worry too much if you spot a snail or two, but in large numbers, they can even destroy a plant by consuming it completely. Typically, if there’s just a moderate infestation, plant growth will be stunted and the yields will not be what you’d expect, especially after taking care of the plant for several months. 

Identifying Snails and Slugs on Cannabis Plants

You can easily identify snails and slugs, thanks to their characteristic slimy bodies. Snails also have shells, making it easier to spot them. Unlike other pests like spider mites that are too small to identify, snails and slugs are easily visible, so you don’t have to spend a lot of time looking for them. 

You can observe these pests crawling very slowly across cannabis leaves, and also across and under the surface of the soil. To identify them further, look for glistening, shiny trails of slime that snails and slugs leave behind as they move across plant surfaces. These trails can be seen on foliage, stems, and even soil.

Next, check leaves for characteristic snail and slug feeding damage, including irregular holes and missing tissue. This type of damage, especially in tandem with slime trails, is a strong indication of their presence in the garden.

How to Fix Holes in Your Cannabis Plant? 

We hate to be the bearer of bad news, but unfortunately, you can’t do anything about the holes in your cannabis plant. Instead, what you can do is take action to remove the aforementioned pests that are creating these holes and hope for a quick recovery for your cannabis plant. 

But how do you do that? You can use the following methods. 

1. Caterpillar BT Spray 

If you’re dealing with a nasty caterpillar infestation — since caterpillars are more common than other pests in cannabis gardens — consider using a dedicated caterpillar BT spray. This is a type of biological insecticide that features BT bacteria, which is also known as Bacillus thuringiensis. 

BT is a nifty bacteria as it offers one of the most effective ways of eliminating and killing caterpillars on plants. The best thing about this insecticide is that it won’t harm your cannabis plant or other beneficial insects in the vicinity too. Additionally, the insecticide also works against other pests like worms, moths, and fungus gnats. 

The moment you spot caterpillars on your cannabis plant, you should apply the BT spray before they end up doing more damage. Do remember that this spray is most effective against small caterpillars that are actively chewing your plant’s leaves. 

Since a BT spray isn’t a one-hit-wonder, you will have to spray it a few more times to eliminate caterpillars from your cannabis plant. So, spray down your cannabis plant once every week until all the caterpillars (or their signs) are eliminated. You can use more of the spray if your plant is heavily infested, but don’t go overboard. 

When spraying the BT spray, it is wise to always follow the manufacturer’s recommendations. Nonetheless, it is also a good idea to keep a few rules in mind. When spraying, ensure you are misting both sides of the leaves and if there is rain, you should spray the spray again since it can get washed away with water. 

One thing to remember is that when you use this spray, the caterpillars won’t drop instantly. The pesticide works by disabling them from eating more, so while they’ll still move around, they’ll eventually starve and die. 

2. Neem Oil

Neem oil is hands down one of the best methods of eliminating not only leaf-eating pests but most kinds of pests from your cannabis plant. This is a non-toxic, organic pesticide that’s made from neem’s essence or oil, and it is effective against pests, fungi, and mold. 

Neem oil contains Azadirachtin, which hampers the pests’ feeding cycle. It also interferes with their hormonal systems, making it difficult for them to communicate, breed, or lay eggs. 

For some insects, neem oil is also fatal. It coats the insects, effectively suffocating them, which is often fatal for some insects. 

Just how good is neem oil? It is effective against over 200 pest species, including fungus gnats, mealy bugs, spider mites, thrips, and aphids. Fortunately, it doesn’t harm most beneficial insects, either. 

To use neem oil, all you need to do is spray down your cannabis plant with a diluted neem oil solution and let it do its thing. Just keep a few points in mind, such as:

• Do not spray it on the buds or flowering cannabis — the strong scent will get on the buds and make them harsh to smoke and smell
• Only spray it during the night; neem oil in light can cause burning on the plant 
• Stop using neem oil at least three weeks before harvest 

3. Diatomaceous Earth 

Another wonderful pesticide you can use to deal with pests on your cannabis plant is diatomaceous earth, which is essentially a naturally occurring powder that is quite effective at killing pests, including crickets and grasshoppers. 

To you, the powder may feel soft and fluffy but it is extremely sharp at a microscopic level. So, once a pest comes in contact with it, the sharp edges of DE puncture its shell and dehydrate it quickly. 

If you want to use DE, all you need to do is sprinkle some of it around the plant and wait for the pests to come in contact with it. Remember to wear a mask when handling DE — it can sometimes be toxic for humans. In addition, it doesn’t work when the soil is moist. 

4. Spinosad 

Spinosad isn’t as effective as BT spray, but it can still work against pests like crickets and grasshoppers. This is also a terrific choice if your cannabis plant is suffering from other pests like spider mites, white flies, or aphids — you can eliminate all of them at once. 

This is an organic pesticide that you have to dilute first and then spray on your plant’s leaves and roots (if necessary). Thankfully, it is completely harmless for the plant but do remember to follow the manufacturer’s instructions for the best results. 

Spinosad is organic and is made from a specific soil bacteria’s fermentation, and it kills pests via ingestion or contact by hampering their nervous systems. But they are only effective for a day once diluted in water, so only make a solution that you intend to use immediately. 

5. Physically Pick Them Out 

Yes, this one sounds like a bit of a no-brainer but have you tried picking them out by hand? If your cannabis plant only has a few leaf-eating insects on them, you can just pick them out one by one. Yes, it’s yucky, but it’s always better to relocate them than try to eliminate them with products. 

6. Beneficial Insects

Finally, you can call in emergency services from beneficial insects that will swoop in and eliminate these creatures for you. This is a terrific solution as it fosters a rich ecosystem in your garden while keeping nasty pests out. These little insects will work as the police on your cannabis plant. 

Some of the best beneficial insects you can use include frogs, beetles, salamanders, lizards, spiders, mantis, birds, nematodes, parasitic wasps, etc.

7. Beneficial Nematodes

Beneficial nematodes are microscopic organisms present in the soil. They play an important role in controlling pests, including caterpillars. Typically, they are available in a liquid form where they are suspended. You can then mix it with water and use it. Like any other application for pest control, follow the instructions from the manufacturer as the amounts may vary depending on the pest you want to target. It’s best to apply the solution on the soil near the roots. In addition, make sure you use it at night if you’re growing outdoors since harsh sunlight can somewhat reduce its efficacy. If you’re growing indoors, use it when the lights are off. 

What makes beneficial nematodes a great choice compared to other types of pest control is that it’s safe to use. They are natural organisms that don’t pose any threat to you, your pets, and other beneficial organisms residing in the soil. What's more, these nematodes remain in the soil for a long time, helping the plant resist pests. 

When you use them in your grow room or outdoors, they actively search for pests. Then, they infect and kill them. They do this by entering the insect pest’s body via its mouth, spiracles, or cuticle.

These helpful organisms are very effective against several caterpillar pests that commonly feed on cannabis plants, including cutworms, armyworms, and loopers. When applied to soil near cannabis plants, beneficial nematodes actively seek out caterpillar larvae in the soil, often in the root zone.

How to Prevent Insects from Making Holes on the Cannabis Plant?

Prevention is always better than cure, so if you want to make sure these insects don’t chew away your cannabis plant, you need to prevent them from reaching your plants in the first place. Here are some tips on doing that:

• Use beneficial insects, as explained above 
• Put up barriers around your plant to keep the pests out 
• Regularly spray your plant down with neem oil 
• Keep the soil healthy and clean and regularly remove any eggs or dead plant matter you find in your garden
• Grow companion plants around your cannabis plant, like dill, chamomile, lavender, and basil, to distract and divert pests 
• Use bug lights or yellow sticky traps around your garden to trap pests that may make their way into the garden 
• Keep the temperature and humidity in check if you can — pests love warm and humid conditions 

Summary: Holes In Cannabis Leaves: Common Pests That Attack Cannabis

If you’re noticing holes in your cannabis leaves, it’s time to start looking for pests like caterpillars, grasshoppers, crickets, snails, and slugs. Use the guide above to identify which bug you are dealing with.

Then, depending on the bug and severity of the infestation, you can use an array of methods, including simply picking them off one by one. They are relatively large insects and often easy to catch. If not, you can use neem oil, BT spray, diatomaceous earth, spinosad, or beneficial insects. 

And once you’ve eliminated them, figure out how they got to your garden in the first place and fix that issue, too. Preventing them is always worth it. As a bonus, if you follow the various steps listed above, you will not only prevent these leaf-eating bugs but many other bugs, eventually leading to a healthier plant and bigger yield. 

Holes in cannabis are somewhat common in some regions, but that doesn’t mean you leave it up to chance or fate. Take matters into your own hands and make sure the only holes that exist in your garden are the ones in your pocket, left by expensive grow lights, not pests and bugs.